Once In A Lifetime
by clawswrites
Summary: Gwaine has always been in love with his best mate, Merlin. When Merlin and Arthur, Merlin's partner of five years, proposition him to help spice up their love life, how can he possibly refuse? But after one night, could he ever consider giving them up?
1. Chapter 1

**Title: **Once In A Lifetime

**Author: **gabe1990

**Prompt(s) Used: **Prompt #48.

**Pairing/Characters:** Arthur/Merlin/Gwaine. Merlin/Arthur. Gwaine/Merlin. Gwaine/Arthur. Gwaine/Leon (at ending).

**Rating: **Mature/NC-17

**Word Count: **1,004 for his chapter.

**Summary:** Gwaine has always been in love with his best mate, Merlin. When Merlin and Arthur, Merlin's partner of five years, proposition him to help spice up their love life, how can he possibly refuse? But after one night, could he ever consider giving them up?

**Warnings/Content Notes:** M/M/M - Threesome sex. Explicit sexual content.

**Author's Notes:** Written for prompt #48 of Gwaine's Quest on LiveJournal.

**Disclaimer:** The characters depicted belong to Shine and the BBC. No profit is being made.

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><p><span>Chapter One<span>

When Gwaine was invited over to his best mates flat that he shared with his partner of five years, he could honest say he did not know why. He had never been invited over before. He was more of a spontaneous kind of person that always seemed to come to early – or late, depending on the time of the week. Of course, he had a few ideas; things like his assistance was needed to fix some electrical appliance that Merlin had broken, as both the men were completely hopeless with the wonders of technology.

The true reason was somewhere in the far reaches of his mind. After all, not everyone gets invited to their friend's place and _assumes_ they are going to be asked to join them in the erotic sex fantasy that would be a threesome.

Well, at least he did not.

Gwaine choked on his drink.

Merlin reached over to pat his friend on the back, concerned. "Are you okay?"

"You-you…what?"

"We, as in Merlin and I, want you to have sex with us both…" Arthur repeated, this time much slower as if talking to a small child.

"Wha-how-what?"

"I'm sure I don't have to explain the mechanics of sex to you of all people." Arthur smirked, amused.

Gwaine gave him a dry look and Merlin elbowed him sharply in the ribcage.

"Of course not, just ask your father," He bit back, causing Arthur to frown darkly and Merlin to give him 'the look' – the one of disappointment. He sighed, running a hand through his wavy hair. "I did hear you the first time…but why? Why me, of all people? I'm your friend…"

…_And I'm in love with you – this is just my luck…_

"We've spoken about this – quite a lot actually – and it's something we both want to do. You of all people should know that _that_ has been my, ah, _kink_ for a while now," Merlin explained awkwardly, his cheeks flushed pink at the conversation. If Gwaine was not so gobsmacked, he was sure he would have enjoyed the pleasant colouring of his face a lot more. All he could do was nod, absentmindedly.

"I want the, ah, third person to be someone I can trust and I care about, that would be willing to join us. Sex isn't just about the primitive need anymore, I want emotion in it…and you were the only person I could think of. Plus, um…" he trailed off, his face reddening.

"Plus, you are incredibly gorgeous and someone that has played a pretty important role in many fantasies on occasion," Arthur finished, a small smirk on his face as he gauged the other man's reaction.

Gwaine had to admit, at least to himself, that the offer was not _entirely_ off putting. In fact, he was pleasantly flattered at the announcement. It was not everyday that two _very attractive and willing_ men confess that he was a source of their wet dreams. But did that really mean he wanted to participate?

It was sad to say, but yes, he was very enthusiastic to help them make a very sticky sandwich. He had known since Year nine of Secondary School that he was in love with the lithe, blue eyed man that was Merlin Emrys. He had never acted on it though, their friendship meant too much to him, and when he had started a relationship with Arthur in their last year, he had gracefully stepped back to allow his best mate to be happy.

Now five years later, he was being offered the chance to have sex with the man he still had feelings for. This was never going to happen again. He'd be stupid to allow the opportunity to pass him by so easily.

And it wasn't as if Arthur Pendragon was not a sight to behold. He was still as gorgeous as Merlin, even with their completely opposite looks, with his wavy blond hair and chocolate brown eyes. He could easily imagine the two together, attached by the mouth and crotch, would become every girl's (and some guy's) fantasies.

Without meaning to, he could see the two bodies, one tanned and the other pale, rocking against each other in a frenzied pattern, engorged and slick cock's sliding against each other. He could hear the husky whispers of approval, encouraging more movement, more friction. He could see their swollen lips, sore from their insistent, arousal ridden kisses, and the indent of nails in Arthur's strong back as Merlin held on for dear life.

Gwaine swallowed heavily at the thought.

"Of course you don't have to say yes," Merlin quickly assured, "We're not going to force you into anything you don't want to do. It's entirely your choice but could you; um…could you just think about it?"

When those pleading eyes were turned to him, he had no choice but to obey. He sighed loudly, mentally cursing himself for being so whipped by a guy that is not even his partner; would never be.

"Of course Merlin. I'll think about it…" he agreed reluctantly.

"Take all the time that you need," Merlin replied, quickly, a grin breaking out on his face, "I don't want you to rush in, undecided, and find you've made a mistake. I want to make sure you're okay with all of this…"

"Merlin, he's already agreed to think about it," Arthur interrupted, resting his hand on his partner's shoulder, "You don't want to overload his system before he's even made a decision, do you?"

Merlin looked sheepish, flushing pink and biting his bottom lip. Instantly, Gwaine's eyes zeroed in on the bitten flesh, looking so red and plump and just damn irresistible. Vaguely, he reminded himself he could have the chance to kiss that Cupid's bow. His heart beat increased at the thought and he did not have enough rational thinking to force it to calm. He blinked once, forcing himself out of his state, and glanced at Arthur quickly, silently wondering whether he had been caught.

Arthur just smirked knowingly.


	2. Chapter 2

Chapter Two

_He bit back a groan, his head tilting backwards against the wooden door and a dull thump noise was heard upon connect. The Knight of Camelot had no idea how this had happened – it was so fast. One minute, he had offered to help Merlin unsaddle the horses after a hunt; the next, he was trembling in where he stood, as the manservant gave him one of the best blowjobs he had ever received. _

_Even stranger was the fact he could see the Crowned Prince in the distance, relaxing leisurely against the piles of hay, his breeches undone and his eyes watching them like a predator would watch his prey._

_It should have unnerved him to be caught by the Prince, but instead it seemed to excite him more. Or maybe it was the fact that, at the exact moment, Merlin had swallowed around the head of his cock. He couldn't be too sure. _

_His hands wove into the silky black locks, tightening and relaxing his grip in an attempt to stave of orgasms (and insanity) for a while longer. Merlin traced his tongue along the underside of his cock and his hips jerked in response. He choked on the sudden movements and Gwaine tried to force himself to still._

"_Don't worry about being gentle with him," Arthur suggested from the other side of the room. His eyes sparkling, one hand smeared pre-cum across his head whilst the other tweaked his nipple. "He likes it rough, don't you Merlin? Loves the burn at the back of his throat and the ache in his jaw when he's done…"_

_Merlin made an unrecognisable noise in response, sending a jolt up his spine. Gwaine moaned loudly, his grip tightening and holding Merlin's head in place as his hips rocked forwards. With a ferocity he did not realised he possessed, he quickened his pace, watching his cock slide effortlessly between the red lips, pulled apart and dripping with salvia. The manservant's eyes were blown, diluted, and the colour blue deeper and darker than it had ever been remembered. Merlin whined around the persistent intruder, his hands rising to hold onto Gwaine's hips._

_Arthur's voice could be heard somewhere in the distance. Although the world was slowly becoming fuzzy and dull around him, the man's husky voice could be heard clearly. "God, that looks so fucking hot…love watching you suck cock…pretty…love to be fucked rough, don't you Merlin? Begging for it…oh yeah…don't hold back…keep going…fuck his mouth, watch…pretty, wet lips…"_

_It was just low spoken words, no real thought behind the words, but it was enough for Gwaine to begin to answer with low murmurs of "yes" and "fuck". His hands shook with the pleasure. He'd never been this wound up before – he just needed his release. He panted loudly and thrust hard into the back of his throat, making sure to roll his hips so his pre-come spread around that pretty mouth. Merlin dug his fingers into the solid hips. _

_The burning in the pit of his stomach strengthened, heating up the rest of his body. His movements become frantic, uncontrollable, as he felt something snap within him, shocking him at the suddenness after so long of just building pressure, and his vision blurred for a moment…_

Gwaine awoke with a start, sitting up in his bed. He was breathing heavily, his skin drenched with sweat, and the weight on his groin caused an ache he was desperate to relieve. He ran a hand over his face, almost as if the cold palm could wake him, and yawned deeply. Slightly disoriented, he turned to his digital clock. The bright red letters stared boldly up at him: 08:59.

_Too early_, he decided and with a groan he dropped back onto his pillows.

Closing his eyes, he turned into the pillow and breathed in deeply, attempting to relax his body, but there was one part of his body that was being stubborn. Cracking one eye open, he raised the duvet cover just enough that he could look down his body to see his erection straining against the confines of the boxer shorts he slept in. He glared down at his 'friend', silently willing him to back down, but it did not work.

_God, that was one hell of a dream_, he mused. For a while, he wondered where it came from. He had never had a historical wet dream before, much less one about Mythical peoples and civilisations. Maybe it was because he had watched the _Sword in the Stone_ the night before, but he could not be certain. After all, the age differences in his dream and in the film were massive.

The dream had felt so real, certainly enough to get a response as if he was a sexual frustrated teenager one more. His eyebrows furrowed at that thought. Even now, as he lay awake, he could almost feel Merlin's sweet mouth around his cock, the indents in his hips and the low murmurs of Arthur's indecent ramblings. His cock twitched in appreciation of the image, and a shudder ran through his body.

He cursed under his breath and pressed the heel of his hand down on the persistent hardness, gritting his teeth to try and stave it off. It did not work. He did not believe in fate – he was not that kind of person – but it would seem it was trying to tell him something. That dream…was that really what he wanted? Did his subconscious make up his mind for him without even realising? Although, if reality was even a fraction of how pleasing that dream was, he had no complaints.

_It's a once in a lifetime opportunity_, a voice in the back of his head reminded him almost coyly. _You know how long you've wanted to have the chance to get at Merlin's arse, so why is it taking you so long to decide?_

_He's my friend; I don't want to make anything awkward between us. Plus there's Arthur…_

_Arthur is more than willing to let you have your way with him and Merlin in any which way you want. Having that man there is a bonus in my books._

_I don't know…_

* * *

><p>Biting his bottom lip with vacillation, his cold hand slid down the contorts of his toned stomach and slipped beneath the elastic waistband.<p>

"…Do you think he'll agree?" Merlin questioned his voice quiet and thoughtful.

He was currently curled against his lover's side, eyes closed and enjoying the feeling of the man's calloused hand running through his hair, massaging his scalp, so softly. Despite the fact he was currently desperate to share another sexual experience with Arthur and Gwaine, he was beginning to wonder whether it was a mistake to include his best friend in the encounter. He did not want anything to change between them, and he was worried that even suggesting that he thought of the man as anything more than a friend would ruin what they had.

It was never a conversation that had come up. He was sure it was common between friends to talk about sexual escapades (which he did) and have had some sexual experiences together – like a mutual wank or something – but this was something much bigger than that. Something much more complicated.

Arthur paused in his movements, thoughtfully, and Merlin whined childish at the lack of contact. With a wiry smile, he continued. "…I think he'll more than likely agree," he finally announced, "Your friend's a horny dog, no denying it, and I'm almost certain he would do anything for you."

"Really?" Merlin raised his head, looking confused, "Why?"

"You're his friend, of course," Arthur lied coolly, inwardly laughing at his lover's complete naivety when it came to how people felt about him. In Arthur's eyes, the fact that the dark man was infatuated with his man was obvious. "People would do anything for their friend's right?"

"Hmm…I suppose so," Merlin mumbled in agreement, snuggling back into the crook of the man's strong neck.

"Plus, there's the fact that Gwaine is not an idiot and, as soon as it was mentioned, he began imagine us together," Arthur added, his voice dangerous. "You could see it when he's eyes darkened. He wants to see us together, my cock buried deep inside you." As if imagining, he began to rock his hips upward and Merlin sighed in pleasure, mimicking the movements.

Their breath became harsh as their need grew, as their movements became persistent and rough. Arthur had stopped stroking his lover's hair and now just gripped it tightly, holding him to his neck that was being nipped and licked mercilessly.

He groaned loudly in annoyance when there was a knock at the door, disrupting them, and Merlin managed to wiggle out of his grip. "Hurry back," he whined almost pathetically, making his lover smirk and wiggle his hips lusciously as he left.

Gwaine stood on the doorstep, hands in his trouser pockets, with an expression of awkwardness or nervousness on his face – Merlin could not be too sure. His friend offered him a slight smile and shuffled closer to the door.

"Gwaine, what are you doing here?" he wondered, quickly glancing at the wall clock he could just about see through the ajar kitchen door, "It's midday – aren't you supposed to be watching Elena's kids while she works?"

"Ah, yeah, she cancelled. Day off, you know…um, _oh fuck it_!"

Before he had anytime to think of a response, or an action, he felt Gwaine's lips pressed firmly against his.

That was all he needed to know.


	3. Chapter 3

Chapter Three

Merlin moaned loudly when his tongue flicked on the roof of his mouth, clinging tightly to his friend's broad shoulders. His eyes were clenched shut and his sense where just filled with something that was completely _Gwaine_. He did not even notice the front door had been shut until he found himself pressed up against it. The suddenness of the impact hurt for a moment but he found he did not care when he felt the sharp nip and pull on his bottom lip.

Gwaine kissed him urgently, his hands drifting to caress the man's backside and using it to support him up the wall. Merlin's legs instantly wrapped around his waist and began to rock their hips together. With a low growl at the back of his throat, Gwaine used his pelvis to pin his friend in place, instantly noticing the erection that was quickly growing against his own. His nails dug into his sensitive flesh harshly. Merlin sucked his tongue further into his mouth teasingly.

"So…I'll take that a 'yes' then, should I?" Arthur's voice drifted from their right. Gwaine pulled away momentarily, much to Merlin's disappointment, to run a dark eye over the blond's relaxed stance in appreciation before moving to bite, hard, on the smooth column of the man's neck. Merlin whined in pleasure and arched his neck to give him more room, his bright eyes meeting Arthur's.

Arthur approached their side, reaching up to run his hands through Merlin's fine hair before caressing his prominent cheekbones and the area just under his eyes. His thumb brushed across his swollen lips, and a moan escaped as the sensitivity of the abused flesh. He then moved to Gwaine, raking his hands roughly through his thick wavy hair, and dragging his fingertip down the length of his face. To the man's credit, he did not react to the touches and merely continued making his mark along the right side of his friend's neck, nipped and licking the wounds in a soothing fashion. Merlin whimpered at the feeling, his head rocking backwards and hitting the door.

"The bedroom," Arthur murmured, watching almost mesmerised by the movement of the man's strong jaw, "Much more comfortable…more room…"

Gwaine detached himself from Merlin's neck and purposely, _slowly_, let the man drop back onto his feet, making sure he was fully aware of all the contorts of his body. He glanced at Arthur and nodded sharply, before he turned and made his way to the bedroom (he knew his way around the flat well by now). In a swift motion, he removed his muscle shirt as he walked, dropping it to the floor just as he turned into the bedroom. The two lovers followed quickly afterwards.

In the small bedroom, Gwaine lay, spread out on the bed, wearing only his white Calvin Kline boxer shorts. His hands rested, interlocked, on his lower stomach, just above the tent in his underwear, and a cocky smile plastered on his face.

"You watched Merlin and me together…" he commented, "Now I want to see you too."

Merlin looked unsure for a moment – he always thought it would be awkward someone watching him like that. Arthur had no such worries; he grasped the man around his waist and tugged him firmly against him. With one hand resting on the small of his back, and the other on the nape of his neck, he guided their lips to meet in a passionate kiss. He coaxed the man gently into letting go of his reservations with flicks of his tongue and nips of his teeth, with the steady rocking of his hips.

Merlin whimpered in pleasure and tugged impatiently at the hem of his lover's shirt. It was quickly brought over his head, revealing his bare chest, dusted lightly with blond hairs. Merlin trailed his hand up and down the man's chest, completely focussed; only changing course to pinch his nipples as the fingernails went past. Arthur shivered.

With a cat-like grace, Merlin slid to his knees, leaving his eyes level with the man's (tight) jeans. He unzipped using nimble fingers and tugged the trousers down his strong legs, letting them pool at his feet. He grasped the back of his knees, scraping the sensitive skin with his fingernails, and removed the clothing from around his ankles. He then trailed his hands upwards, teasing the inside of his thighs and resting his head on his upper thigh, watching his lover's impressive cock harden and strain.

He smiled almost teasingly, before tilting his head forward just enough that he could place the tip of his tongue against his slit, pressing firmly to get a taste before pulling back quickly. Arthur groaned and rocked forward almost pleadingly, the blunt tip hitting Merlin's cheek. He grabbed his lover's hips, holding him in place, and attentively closed his mouth around the throbbing head. He held himself there for a moment before, suddenly, sucking the man's tip deeper into his mouth, moaning at the taste of pre-cum that leak onto his tongue. His tongue laved at the underside of the heavy cock, tracing the vein, taking more of the man into the wet cavern. Arthur cursed his breathing harsh, his eyes darkened with pleasure, as his hands moved to knot into his lover's black hair.

Gwaine shifted on the bed, craning his neck, desperate for a better view. His erection pushed against the seams of his boxers and his hands itched to reach for it. The urge was too strong, the pressure too much to bear, and he slide his hand under the waist band to grasp the base of his cock tightly. The image his mind had concocted was nothing compared to the real thing: the straining tendons, the skilful movements, the colour contrast between skin and hair. Arthur's moans, throaty and husky, seemed to echo the room, causing jolts of pleasure to move straight to his cock. He watched the movement of Merlin's jaw, of his harsh bobs, and found his hand mimicking the actions with perfect accuracy.

He had to admit he found it strange, watching his two of his friends together in a sexual way. Before he had been propositioned, he never would have thought to consider the two of them together. It was like forbidden territory, a line that should never be crossed, but now, he wondered how he could never have thought about it.

It was a truly amazing sight.

Arthur tightened his grip momentarily before he managed to open his eyes a crack to see Gwaine spread out on their bed, staring at them intently, whilst he pleasured himself at a slow and leisurely pace. It was as if he suddenly remembered that they were not alone. He shivered at the thought of Gwaine watching Merlin and him together, so intimately, and his arousal spiked. With some reluctance, he removed his cock from his lover's wondrously brilliant mouth, causing Merlin to whimper in disappointment. He pulled the man to his feet and roughly removed his tee shirt, giving him a hint to strip. Arthur watched Merlin remove his clothes for a second, before casually moving to kneel at the foot of the bed.

Gwaine paused for a moment, tilting his head back to look at Arthur who merely smirked down at him. He skilfully managed to bend down and steal the man's lips into a searing kiss. Gwaine moaned quietly and his movements ceased completely as he reached both hands up to cling to Arthur's blond head. Merlin watched the two together for a moment, liking the sight of their strong jaws jerking against each other made when they slide their tongues past the others lips, before he hurriedly removed his underwear (he got his long legs caught in the fabric for a moment, but soon fixed that problem) and joined them on the bed, on Gwaine's free side. He remained silent, just watched the two men together with keen interest, before one hand moved to trail along Gwaine's arm, bring out Goosebumps on surface of his flesh. Merlin pressed his body against his friend's body, his hand tracing upwards to brush the thick hair away so he could nibble on the edge of his ear. Gwaine groaned and the kiss became sloppy. Merlin tugged experimentally on the lobe and licked the flesh. His hand moved to cup the man's strong jaw, feeling every movement, every muscle, and was completely mesmerized by the feeling.

Arthur dominated Gwaine, sucking on his tongue before releasing it, as he trailed his hand down the man's sensitive side and pinged the elastic waistband harshly, making him yelp in surprise.

"Off," he ordered.

Merlin clung to Arthur when Gwaine moved, leaving his body cold. He whined and nuzzled the man's neck, biting down on the crook, and rubbing his cock against the side of his thigh. Arthur's breath caught at the feeling and tugged roughly on the man's hair. His hips mimicked the thrusts of his lover. Gwaine threw the offending underwear somewhere into the corner of the room, and turned back onto the bed. He copied Merlin's actions from before, pressing his body against the man's back and making sure that his cock rested in the crease of his arse.

"So, when you asked for this threesome, what did you have in mind?" he muttered huskily, rolling his hips forward ever so slightly and pulling back before Merlin could get anymore simulation.

"_Fuck_ _Arthur_…_Gwaine_…_ah_…" Merlin muttered, biting down harshly once more.

Gwaine used his hand to make a pathway along Merlin's revealed side, and grasped his cock at the base, stopping him mid-thrust and pressing him further onto Gwaine's own cock. He whimpered in disappointment and struggled for a moment, only stopping when Gwaine tightened his grip as if in warning. His head tilted backwards onto Gwaine's shoulder.

He arched an eyebrow. "Is he always this desperate?" He questioned, his voice practically dripping with arousal.

"Oh yeah…" Arthur mumbled absent-mindedly, as he turned further into Merlin so he could trail down his body, first with hands and then with lips. Goosebumps rose on the man's pale skin at the feeling. Arthur paused, his hands on the centre of Merlin's stomach, feeling the muscles contract, and looking up at Gwaine, "Do you mind holding him still?"

"Not at all," Gwaine agreed quickly, holding the lithe body firmly, the only real grip being the one holding his cock pointing outwards into the cold air.

Arthur grinned mischievously, his blue eyes sparkling, before placing an open mouth kiss on Merlin's nipple. The tip of his tongue flicked across the nub, coaxing it into erection before he bite down on the pebbled nipple. He rolled it between his teeth, pulled back before releasing it. The cold air chilled the salvia and Merlin gasped. Arthur then repeated the action on his other nipple. He licked each one once more, just to ensure there wetness, and pulled back as if to admire his work. He flicked each one and Merlin cried out in surprise, his back arching slightly. Grinning at the reaction he caused, Arthur rolled the nipples on the palm of his hands to prolong the feeling.

"God…ah, _Arthur_!"

"Well, he seems to like that," Gwaine muttered.

Arthur chuckled throatily. "He has unusually sensitive nipples. Doesn't he look beautiful, hard and pleading?"

Gwaine looked down at his shoulder to see Merlin gazing up at him, his wide blue eyes darkened with lust, his lips parted with his heavy breathing, his cheeks flushed a light pink colour. God, he never thought he would ever see Merlin like this, so needy and desperate – it was better than he could imagine. He hummed in agreement, raising his free hand and sliding a finger between those parted lips. Merlin latched on instantly, pulling and sucking the limb further into his mouth, scraping his teeth across the skin. He moaned, muffled around the finger, when he felt Gwaine's cock grow between his bare arse cheeks.

Arthur continued his journey southward. His hand remained in place, slowly rolling the nipples round the centre of his palms, whilst his mouth mapped out his abdomen thoroughly, biting and licking in random places to leave landmarks on the smooth skin. Merlin's jutting cock hit the underside of his chin and he pulled away slightly to stare down at it. It was thin – Gwaine's hand could hold the base loosely in one hand – but it was made up with the size, long and unbelievably hard. He buried his face into the coarse hair and breathed in the musky smell. Merlin whimpered.

Arthur pulled back and flicked his tongue across the leaking head of Merlin's cock. The action caused even more pre-come to leak from the slit than before. Merlin sucked harder on Gwaine's finger. He took the head into his mouth, bobbed his head once, twice, and pulled back. The pre-come and spit glistened on the head in the light. Arthur blew on the head for a long while, causing Merlin to curse loudly, before he opened his mouth to take the muscle as far done his throat as he could manage. His lips brushed Gwaine's knuckles and the head bumped the back of his throat. He swallowed around the tip teasingly and pulled away slowly, tracing the pulsing vein on the underside of his cock with his tongue as he moved. A saliva trail was left from his lips to the wet cock. He wiped the spit away with the back of his hand.

"How does that feel Merlin?" Gwaine muttered darkly.

Merlin released a guttered noise. "…Good, hot…_ah fuck_…Arthur…_please_…"

"Please what?" Arthur teased.

"Fuck me…suck me…for God's Sake, _do something! Anything! Both of you!_"

"…I want to taste you first, is that okay?" Gwaine asked quietly. Before he had been propositioned, when Merlin was one of his many fantasies that were concocted by his brain to wank along with, he had wondered what he could taste like; what it would feel like to have the weight of his cock in his mouth and his come sliding down his throat. He had always felt embarrassed that he would want to know such a thing about his friend, never brought up that particular idea no matter how close he and Merlin were but now, he had the chance to answer the burning question. He could not just let it pass him by.

Beside, it was not as if Merlin was opposed to the idea. In fact, he groaned deeply, his eyes darkened, and he nodded quickly in response. Arthur arched an eyebrow at him – _again with that damn knowing look_, Gwaine thought mildly annoyed – and released Merlin to his friend's care.

Gwaine rolled Merlin onto his back, and moved swiftly to kneel between his legs. The man's cock had dropped, as if in defeat, onto Merlin's flat stomach, pre-come pooling in his belly button and his balls pulled up to his body in anticipation. Gwaine could feel his mouth water. Nervously, he licked his lips and glanced at Merlin's glassy eyed look one more time, before he lowered his mouth to take his head into his mouth. It was heavy, not comfortable; merely unusual – if he sucked the cock of one of his bed partners, they were usually much thicker but nowhere near as long – but he quickly got used to the feeling. He breathed in through his nose just before he moved his head downward, taking more of the man's pulsing erection into his mouth, pausing only when the head hit the back of his throat. He grazed his teeth along the base; wrapping his tongue along the heavy shaft. He managed to rub the leaking tip on the ridge just above his throat passage. Merlin moaned loudly and his hips jerked upwards. Gwaine spluttered for a moment, not prepared for the sudden movement, but placed his arm across Merlin's thin waist to prevent it from happening again. He sucked long and hard.

Merlin's back arched and he turned his pleading gaze onto Arthur, who was watching the men together with dark eyes, his hips rolling involuntarily. He reached out and pulled Arthur on top of him, his strong legs straddling his chest, his cock resting across his collarbone. Merlin hand's rose to grip his partner's hips tightly.

"I want…I…" he shuddered when Gwaine nipped at the skin on the underside of his cock, "I want you…to, _ah…fuck _Gwaine…while he – _ah God_ – fucks me…" he used his grip on Arthur's hips to drag him closer, his cock sliding between Merlin's parted lips to his excited tongue that lapped eagerly at his come.

Arthur juddered forward, and gripped Merlin's shoulders tightly, his fingernails in bending in the skin. He let out a shaky breath and allowed Merlin to roll his hips forward, to control the movement of his cock passing those swollen lips.

"Gwaine…you to, _ah_…to fuck him you…prepare him! _Fuck_…lube in the, _ah gods_, bedside…" Arthur instructed pathetically, waving his hand vaguely in the direction of the table, his eyes totally focused on watching Merlin take control.

Gwaine released Merlin's cock with an obscene pop, letting it drop heavily onto his lower stomach, as he stood on shaky legs to receive the lubrication. He fumbled around in the drawer, distracted by the sound of slurping spit and Arthur's throaty moans of appreciation. When he finally managed to get a grip on the tube, he returned to his place and placed Merlin's legs over his shoulders, meaning his legs were parted wider leaving easy access to his rim. He stared at the muscle for a minute, watching it clench and loosen at random intervals, before he was able to move. He smeared a generous amount of the fluid onto his trembling hand, rubbing it between his fingers to warm it up slightly, before he _gently_ and _slowly_ pressed his forefinger past the rim.

It was tight and hot, burning even, and his finger slipped through easily, reminding him that Arthur would have been in the same position he was at this very moment. He shivered at the thought. Taking a breath, he moved the finger, swirling it around in a circle to stretch the area. He added another finger, scissoring the hole open - then a third and a fourth. Merlin clenched his muscles around the fingers and jutted out a broken moan around Arthur's cock.

Arthur groaned loudly, his hips snapping forward, forcing Merlin's lips apart. He mumbled an apology and let out a shuddered breath. "Please tell me you're, _ah_…nearly finished…can't – _fuck_ – last much longer…"

Gwaine nodded furiously, the pressure of his cock against his stomach and his tightened balls suddenly too much to handle any longer, and added "uh, yes" when he realised Arthur could not see him with his back towards him. Arthur muttered something that sounded like "finally" and, in a swift movement, he had moved Merlin onto his hands and knees. Merlin buried his head in his pillows, inhaling Arthur's scent that had been imprinted into the fabric, and angled his hips upwards, presenting his arse to his friend.

Gwaine positioned himself easily, rising up on his knees. He rubbed the head of his cock against the winking hole, and paused before he could push in fully. Merlin made a noise of objection at the sudden lose of movement.

"Um, can I…?" he made a hand gesture towards his hard cock and his friend's entrance.

Arthur paused, thoughtfully. "Ah, I don't know…"

"_Just fuck me already! I don't give a shit just for God's sake_…" Merlin snapped, trailing off into a whimper of desperation. Gwaine took the statement as a clear green light and, after gently easing his head into the loosen rim, he trust forward forcefully, burying himself completely into the space. So tight; so hot; too much, too fast. He had to grit his teeth and breathe out heavily to stave off the orgasm that was threatening to overwhelm him. Merlin gapped soundlessly, pleasure swarming out over his features. Gwaine was _thick_, much thicker than he was used to. He felt so_ stretched_ - so _full_.

Arthur knelt behind Gwaine's trembling form, gripped his head and used it to force the man forward, bending over Merlin. They both gasped at the change of position. Arthur ran his finger along the cleave of his arse cheeks, circling the hole before pulling back with a surprised groan.

"You stretched yourself," he stated huskily.

Gwaine chuckled breathlessly. "Ah, yeah…I was hopeful…"

"Very hopeful, indeed," Arthur muttered moving to slip his thumb into the hole, testing how far it was stretched. His thumb slipped passed easily. He crouched downwards to appreciate the work, to see how much more needed to be done, and watched the sudden clenching of the delicate and private area. Teasingly, he pressed the flat of his tongue across the rim, pulling back and allowing the tip to flick across it. Gwaine groaned and dropped his head to rest between Merlin's shoulder blades.

"Fuck…" he cursed loudly, his hips buckling backwards instinctively making Merlin release a moan of surprise, "…_Would you just hurry up and fuck me_?"

Arthur grinned, amused, before straightening up onto his knees once more. He rubbed his head purposely across the stretched rim before, after what seemed to be an eternity for Gwaine, pushed in. He did not stop, until he was in to the hilt when he stopped, hissing under his breath and panting heavily as he struggled to regain control over his own body. He had to keep his body tense, rigid – which was difficult enough as if was without the persistent twitch of the skin around him.

Gwaine clenched his fists tightly and gritted his teeth. He'd had group sex before, it was not something amazingly new for him, but this was something much different. Maybe it was because it was with people he knew personal; maybe it was because it was just _Merlin_ and _Arthur_. He did not know, but he found he did not care too much because of the _intense pleasure_ he was currently feeling at being filled from both ends. Merlin mewled beneath him, too lost with desire to do much else, and he could hear the heavy, laboured breathing in his ear. His senses felt overwhelmed and he wanted desperately to move, but as the middle party in this particular situation, he had to wait for his top to start a rhythm.

Although he did thrust backwards, just a little, when he felt it was taking too long.

Arthur reached up to grasp his friend's thick hair and interlock his fingers with it, before he roughly pulled out and slammed back in. The force of the sudden movement caused Gwaine to jerk forward and unexpected into the unknowing bottom. Merlin's cry of surprise caught in this throat, just a sharp sound, and he rocked backwards. Gwaine bit down on the arch of his neck roughly. Grinning to himself, the blond began to pick up a strange, uncoordinated rhythm, using his grip on his friend's hair as an anchor. One minute it would be fast and rough, the next slow and sharp. It was not exactly what Merlin or Gwaine wanted but they had to admit, the changes kept them interested. It brought them close to orgasm and to a sudden stop, before leisurely bring them back to the point of no return or the process to begin again.

Say what you want about Arthur, but even Gwaine had to admit, he knew what he was doing.

Merlin was shaking from the whole experience, wanting nothing more than the release all the tension that was coiling and tightening in the pit of his stomach. He'd been on edge for too long and he did not have enough self-control to wait any longer. He sobbed against his pillow, the noise muffled, and he rubbed the head of his cock against the smooth, coldness of the silk sheets below. Once more, he felt the jolt of just pure want shoot through his body as the blunt head of Gwaine's cock pushed firmly and incessantly against his prostate, and he knew he was on his wit's end.

Arthur gave one more firm and straight jerk of his hips forward, nudging his prostate head on, and Gwaine mimicked the movements into the man below him. Merlin was the first to come apart. He let out a throaty cry, his body shaking vigorously, as he spurted across the sheets and his chest. His muscles clenched around Gwaine's erection, holding him in a tight vice-like grip. He groaned, the noise deep and husky, and climaxed as he continued to thrust, abet jerkily, into the tight channel. Arthur tightened his grip on Gwaine's hair and pulled on it roughly, jerking his head upward, and gave three short and sharp rolls of his hips, before he shuddered out his orgasm.

With a sense of sated relief and completely boneless, the three men collapsed on their shaky legs.


	4. Epilogue

Epilogue

_One year later…_

The muscles in his neck tightened as Gwaine threw his neck backwards, when Arthur skilfully deep throated his cock. He cursed loudly as the blond smirked as much as he could around the base. His hands knotted tightly in the thin strands of hair and his hips jerked upwards involuntarily. Although his eyes were clenched shut, he could see the bright flash of white light beyond the closed lids.

"_Merlin…_" he gritted out. He managed to crack one eye open.

"What?" Merlin questioned an amused smile on his face and his blue eyes twinkled as he lowered the camera from his eye level, "You said Leon wanted pictures…"

It had been a year since the day that Gwaine accepted the proposal of joining his best friend (and long-time crush) and his life partner in their bed. He would admit, he'd had his reserves about the arrangement, but he was glad he had agreed. It had been awkward at first – these we're his _friends_, and people generally didn't have sex with their friends. This silence had filled the room once the three had regained their breath, and no one could really look each other in the eye. Merlin had shifted first and winced at the twinge in his backside. Gwaine tilted his head in that direction and muttered an apology. Then Merlin had smile brightly at him.

"_No need to be sorry. I like this feeling – it's the aftermath of a good thing. It'll help me remember for a few days, and I don't want to forget this. I was right – threesomes are not better in the imagination. I'll take mine with a healthy dose of reality, thank you very much."_

_Arthur barked out a laugh. "I second that notion."_

_Gwaine glanced better the two of them, amused. "My God, you two are completely mental, do you know that?"_

"_Oh, we know, but that's why you love us!" Merlin paused for a moment, "Hey, are you still coming 'round on Sunday for dinner?"_

_Gwaine blinked. "I guess…"_

"_Brilliant – you see I have this new toy we could try out…"_

And that was pretty much the start of this strange relationship. Every once and awhile, on an unplanned weekend, the three would meet up and almost automatically fall into bed with each other. It became a habit – an amazingly pleasurable habit – but in a way, Gwaine believed anyway, it was good for them. Within the year that this arrangement had lasted so far, his terminal crush on the unattainable Merlin Emrys had dwindled into nothing but a warm feeling that he was sure was somehow connected to a strong friendship (even one with benefits). It was the same with Arthur; a contented feeling instead of the reluctant resentment he had felt before.

It had also helped him in the relationship department. He was never good with relationship; didn't really like the idea of commitment and being tied to one person. It seemed like a lot of trust to put into one person, and he'd never felt something so strong for someone that he was willing to give himself completely to them. Not even with Merlin. But seeing him and Arthur together…it was something different from everything else he'd experienced. Never had he known a normal, stable relationship (at least, as much as they could be) to willingly accept another person into their bedroom, into their personal lives. It was only something he'd heard about on television – okay, porn channels, but it's the same thing really. He could see how relaxed both Merlin and Arthur were about the whole thing. It was like everything was the same as usual, even though it wasn't. Not completely anyway.

And now he had Leon. He'd met the tall man at the firing range. He'd gone there to let out all the pent up anger from the day when he saw the man in the cubicle beside him. He had (rather skilfully, he believed anyway) asked the man to help him with the clips in the gun as it's "my first time here". Leon had quickly agreed.

"_Thank you…you're good at that…" Gwaine commented absentmindedly. _

_Leon shot him a smile. "I should be. I've been doing it for six years…I, uh, I'm a cop…"_

"_Really? Well, you certainly have the build for tackling criminals…" He commented, eying him slowly, "I take it you enjoy your work?"_

"_I meet…interesting people…"_

"_Um, well you can add another person to your list of 'interesting people', and feel free to tackle me _anytime _you feel like it," Gwaine grinned charmingly._

_Leon chuckled, nodding slightly. "I'll be sure to do that…"_

They had been together for nearly five months now, and he had enjoyed their time together. Leon was relaxed and laid-back, was never overly possessive or judgemental. When he had pointed that out, the man had merely laughed and commented that he was known on the force as the "Gentle Giant". Gwaine took great pleasure in teasing the cop about that. Even when Gwaine had told him about the arrangement between himself and Merlin and Arthur, Leon had looked thoughtful for a moment and asked for pictures.

Hence the reason Merlin was now blinding him to distraction with his digital camera.

"Seriously Emrys, stop with the pictures already," Gwaine managed to get out through gritted teeth and laboured breathing.

"Just one more – the money shot," Merlin winked playfully, bending down to nip at the shell of Gwaine's ear and suck on Arthur's earlobe.

Seeing that as his cue, Arthur hollowed out his mouth and sucked hard. His tongue wrapped teasingly around his shaft, the tip flicking across the pulsing vein on the underside. Gwaine cursed, and used his grip on Arthur's head to bury himself roughly – although he didn't mean to. Arthur wasn't fazed and slowly scrapped the edges of his teeth across the sensitive skin, pulling himself away. Just as he had expected, Gwaine let out a strangled cry as he reached his climax. From the distance Arthur had pulled away to, the cum splattered covered the contorts of his pale face. Through the haze of pleasure, he saw one more bright flash of light and was silent glad the 'photoshoot' was over. He leisurely opened his eyes and was greeted by the sight of Merlin carefully licking the evidence of his release from his lover's face. He groaned quietly and rolled to sit on the edge of the bed.

"Don't have enough time to watch that right now," he mumbled, shaking his head as he pulled his boxer shorts on over his hips, "I meant to be meeting Leon for dinner, and I still need to go home and shower."

Arthur chuckled hoarsely. "When do you want these pictures?"

"Whenever, I'm sure Leon can wait for a few days," Gwaine smirked. He stood up and tugged on his jeans, pausing to re-buckle his belt, "I'll come over next Sunday. It's Arthur's turn to make dinner right?"

"Actually, it's mine," Merlin corrected.

"On second thought, I might just stop by McDonald's on my way here," he joked.

He heard a short laugh and an outraged gasp behind him before he felt a pillow hit the back of his head. He smirked at his friend.

"Don't worry, I'll make sure he doesn't poison us all, as usual," Arthur assured, reaching to wrap his arms around Merlin's shoulders and drag his naked body against his own.

Gwaine picked up his t-shirt from the pile on the floor. "I'll leave you two alone to make kissy face at each other."

"Tell Leon we said hello," Arthur called as he left.

"You should bring Leon for dinner. I'm sure he'll enjoy the _evening entertainment_," Merlin added.

Gwaine remained silent, already planning what the four of them could do next Sunday…

**A/N: ****And it is finally done. I know it may be kind of sort but I wanted it that way, so these four chapters are all I planned. I may be tempted to write a few short stories or sequels if I get enough requests for them :) **


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